I have a known leaky air conditioner on my truck--it holds coolant for about three days before dumping it out altogether. I would be more concerned, if not for the fact that I will only be owning this truck for another week or so as I take it to a climate that will not need A/C. Until then, I need to take a cat with me, so I'd like the A/C to work and want to just dump R134a refrigerant in as I drive.

The following are pictures of my truck's engine. I -think- the valve in the middle picture is the valve I need to connect to, but I am not certain.

Your best bet is to bring it to a mechanic . They have refrigerant that can seal up holes and also tell them where the holes are. There products are better then the ones you buy at the store.posted by majortom1981 at 11:24 AM on August 1, 2011

Did you take a cap off the green valve in the picture ?

There are typically two valves for AC refrigerant on your car. They look like tire/bike-stem valves (schrader valves). One is the hi pressure, one the low pressure valve. You want to add to the low pressure valve.

I don't see both in your pics, and the green valve doesn't look quite right. So keep looking. On my cars, I believe BOTH valves are on a metal tube, but one may be on the compressor.

So, buy the can of R-whatever at the store (it should come with a short flexible tube), identify the low pressure valve (anything in your manual about that ?) plug in and empty the can in.posted by k5.user at 11:26 AM on August 1, 2011

You can buy refrigerant at the car parts store and it's pretty simple to add. If you're going to have to do this multiple times it may be more cost-efficient to buy a kit with reusable connectors and a few more cans rather than the all-in-one sort of solutions with a connector already attached.

The specific location of the connector shouldn't be too difficult to suss out; any kit will have images and the connectors are deliberately different for high and low pressure sides so you don't blow your own face off.

The folks at most car parts shops will be helpful. During low traffic times I see them walk out with people to eyeball stuff and provide a little up-close direction for a short period. This should qualify.posted by phearlez at 11:43 AM on August 1, 2011

This is so easy to do that even my wife can do it (I showed her how).

The basic thing to do is get a can from the store with the attached hose and gauge, and read the directions. They are really simple to read and understand.

Basically, though, you turn on your car; turn the A/C on MAX; connect the hose to the low-pressure side of the A/C (e.g. the only connection the hose will fit onto); turn the dial on the gauge so that the temperature part of the gauge matches the ambient air temp; turn the gauge itself to puncture the can; when the compressor engages (on its own) the gauge will read the pressure; shake the can, tip it sideways, squeeze the trigger or unscrew the puncture pin (depending on the can); let go of the trigger/re-screw the can; check the gauge; if it's in the green, you are good, if not, add more. Don't overfill, so take your time!

None of the above will make any sense until you have the can right in front of you, though, so, again, just read the instructions on the can.

It should cost you under $25 all said and done. I have a car that I have to "re-charge" once every three years. I already have the gauge and hose, so spending $11 on a can of R134a every three years is much cheaper than getting it "fixed."posted by TinWhistle at 12:45 PM on August 1, 2011

You would need to do something epic stupid to cause a problem. As phearlez alluded to, there are both high and low pressure sides and connecting a can with contents at low pressure to the high pressure side would cause, um, an issue. However, there shouldn't be a way to do that.

Just make sure you don't hold the can upside down after you connect it, because A/C compressors don't, by definition, like incompressible things like the liquid r134a that lives on the bottom of the can. You're basically waiting for the liquid R134a liquid to convert to gas and flow out of the can and into the A/C system. It usually takes 5-10 minutes for this to take place and you're shooting for a final pressure (if a pressure gauge is included with the r134a) of anywhere between 20-45 PSI.posted by pjaust at 4:04 PM on August 1, 2011

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